Planted buffer zones protect watercourses

Welcome, listeners. Today, we’re going to talk about protecting waterways from siltation by creating vegetated buffer zones. We’ll present two cases: that of the Mouhoum river in Bendougou, a village located about twenty kilometres from Dédougou in the Boucle du Mouhoun region, and the case of the Sinlo dam in the Cascades region.

In this program, we talk to Mr. Somwaoga François Zida, a young farmer who used to cultivate cereals on the banks of the river. Today, he has transformed his field into a mango and orange plantation. Also on the phone is Mr. Sanley Sory, former chairman of the village watchdog committee set up to protect the riverbanks and water in part of the watershed. Mr. Sory will tell us about the vegetation strip that the users of Sinlo have planted to prevent the siltation of their dam. In our studio, we welcome a specialist in managing water resources. Amadé Zongo is a geologist and technician with the Mouhoun Water Agency. He will talk to us about the siltation of the Mouhoun River and the effectiveness of plant strips to prevent sand and other debris from being transported down the river.

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Let’s start with Mr. François Zida. He’s a farmer in the village of Bendougou, about twenty kilometres from Dédougou, the capital of the Boucle du Mouhoun region in western Burkina Faso. You used to farm on the banks of the river, but since 2016, you no longer do so.

I no longer cultivate on the banks of the river because I realized that it was contributing to the degradation of this important water source by increasing siltation. By stirring up the soil, I was helping to transport of soil into the river. We noticed this because the depth of the river was decreasing every year and dried up immediately after the rainy season. With the help of awareness-raising efforts by technicians from the Mouhoun Water Agency, we realized that it was our agricultural activities that were causing this situation. Since 2016, I no longer farm on the banks of the river.

And what have you done with what is now your old field?

Thanks to the support of the Mouhoun Water Agency, my former maize field has now been transformed into an orchard. Since 2016, I have planted about a hundred fruit trees, including mango, tangelo, cashew, and a few baobab trees. The orchard is bordered on the river side by a thorny plantation that serves as a living hedge.

Do you think trees protect against siltation?

Of course! Trees protect against siltation. They slow down the force of water runoff and keep the land firm. Wind and rainwater can no longer carry sand, soil, and other debris into the river. The fence of thorny trees strengthens the ability of the vegetation strip to reduce siltation of our river. It helps stabilize the banks but also protects the orchard, so this fence is just behind the fruit trees, closer to the river and about ten metres from the trees.

Tell us, Mr. Zida, how do you plant these trees to protect your river from siltation? Is there a special planting technique?

The trees have to be planted in what is called an easement strip. The trees must be planted at least 40 metres from the high water mark. This is not the river’s edge as such. This prevents the trees from being in the water during floods. In fact, the trees extend from 40 metres from the high water mark to 100 metres from the high water mark. I planted the trees in parallel lines along the river, staggered to slow the flow of rainwater. The trees are spaced about ten metres apart, as are the lines.

What has planting trees actually changed in the situation of the river?

Many other producers have planted trees to combat the siltation of the river. If we hadn’t done so, the river would certainly be blocked in places and the water would leave its bed and flood fields or even villages far away. We feel we’ve done our part. Now it’s our turn to raise awareness among other farmers who are still cultivating along the river banks to stop cultivating and plant trees instead. These trees will not only protect the river, but will also earn us more than growing cereals. This year, 2023, I have earned more than 200,000 CFA francs ($329) from my orchard of mango, tangelo, and cashew trees.

Mr. Zida, by giving up production on the banks and waiting for your trees to produce, how much do you estimate you will lose?

I didn’t lose anything. I gradually stopped producing on the banks, just long enough for the trees to grow and start producing. On the advice of the technicians, I changed my cultivation itinerary by ploughing parallel to the river bank. It is worth noting that in our area, land is always available. So I found a small piece of land elsewhere to make up the difference.

We’re now with Sanley Sory, former president of the local water committee in Sinlo. Mr. Sory, how do you compare the past situation of your dam with the present situation?

Let me start by saying how important this dam is to the village of Sinlo. Suffice it to say that without this dam, life here would be difficult, if not impossible. The village relies heavily on this water resource. People grow vegetables, water their livestock, and draw water for various needs. In addition to the income we generate, the dam has greatly improved our nutrition.

Going back to your question, it has to be said that the situation at the dam was very worrying. In some places, the water level in the dam was as high as five metres. When we started to plant the vegetation strips, the water level wasn’t even one and a half metres. We were very worried about the possibility of flooding. Today, the dam is in better shape. It’s surrounded by plantations of trees, shrubs, and grasses that are holding back the sand and all kinds of debris that were being transported into the water. It doesn’t dry out as quickly as it used to, and I hope it doesn’t dry out again. In any case, we’re going to do everything we can to stop the sand from getting into our water hole. That’s why, with the help of the water agency of the Cascades Region, we have started reforestation to protect our dam.

When did you start planting and what species are you planting?

We started planting in 2017. We’re planting mainly mango, cashew, and melina trees along a stretch of almost two kilometres long and three hundred metres wide along the banks of the dam. The scientific name of the melina trees is Gmelina arborea.

What do these mango, cashew, and melina trees do for you?

It’s true that our aim was to protect the banks of the dam. But we chose to plant these species so that those who farmed on the river banks could use them when they matured. The mango and cashew trees provide fruit, while the melina trees provide valuable timber. This helped us convince the riverbank dwellers to abandon riverbank farming in favour of planting these trees. We have planted over 250 mango trees with a success rate of over 65% for the entire plantation.

What is your assessment of the level of siltation at your dam now?

It’s true that planting trees on the banks of dams can help protect them from siltation. But only if we stop cultivating these banks. Far behind the plantation, one kilometre away, we built a barrier of stone cordons on land that slopes down to the river. The barrier captures soil to stop siltation of the river. These stone lines are built upstream of the dam. We did this with the help of agricultural technicians. We’ve noticed that the siltation of our dam has been greatly reduced. It’s a fairly effective technique.

Are you still planting trees on the banks of the dam?

Yes, of course. We have to keep planting. We have to replace the dead trees and continue to reinforce the planting to better contain the siltation. We continue to plant.

What advice do you have for those who want to protect their dams or rivers from siltation?

We have to select good species to plant. We need to plant useful species that can be used by those who previously farmed on the banks. This encourages them to leave the banks for planting. If they don’t, they will come back and grow crops on the banks.

It’s not enough to plant and leave. You have to protect these planted trees so that they can grow. To do this, the owners of these plantations encircle the trees with small fences made of wood and straw, or simply with thorny branches. But the best protection is surveillance. Otherwise they will be grazed by wandering animals, especially in the dry season. Never be discouraged. Even if there are difficulties, persevere, make the effort and the results will follow.

Thank you, Mr. Sanley Sory. Let me recall that you are the former chairman of the local water committee of Sinlo in Comoé province. Let’s end this program with Mr. Amadé Zongo, a geologist with the Mouhoun Water Agency. Tell us, what was the state of the Mouhoun River before the plant buffer zones were created?

In 2016, we were very concerned about the siltation of the river. I wondered if there would still be water in the river in coming years if nothing was done. Just after the rainy season, water in the river becomes scarce because of the sandy soil.

The siltation of the Mouhoun River is quite worrying, as you said. But what is causing this siltation?

Farming practices along rivers and in the watershed are responsible for the siltation and pollution of the water. By stirring up the soil with their plough or hoe, farmers break it up, and rainwater carries this soil into the river. Farmers also use fertilizers and pesticides on their fields. This causes water pollution, which can reduce the amount of oxygen in the river, killing fish and other aquatic species. This practice also leads to the development of invasive plants in water bodies. That’s why we advise farmers and local residents to plant trees and grasses along the banks of waterways to prevent siltation and pollution.

How effective are these plant strips against siltation? Do they effectively protect against the degradation of rivers and other water bodies?

Vegetation strips are very effective at preventing siltation. Good results have been achieved in areas where the local population has been involved. Since farmers like Mr. Zida started planting trees and stopped tilling the soil, the banks have stabilized and the river has become less prone to siltation. Sand and other debris are no longer visible in the river. The water quality is also good. We are testing the water in the lab to confirm this.

Farmers like to grow crops near water sources because the soil is fertile and there’s water right next to it. How have you been able to persuade farmers to stop growing near water?

It wasn’t easy. In fact, the farmers close to the water have the best yields. We sensitized the people living on the banks of the river and made them understand that if they continued to farm on the banks, the river would disappear in a few years. We explained to them the danger they were running by continuing to cultivate on the banks.

We also explained the benefits of planting trees. These are mainly fruit trees. They will not only protect their water source, but will also provide them with income. Many farmers have understood this and agreed to convert their fields into orchards for their own benefit and that of the whole community. We’re happy to see the community’s attitude changing.

Thank you, Mr. Zongo, for your comments. Thank you also to the other guests. We come to the end of this radio program on fighting the siltation of water sources by planting buffer zones. Planting trees on the banks of rivers protects them from siltation.

You’ve heard from farmers François Zida and Sanley Sory. You’ve also listened to Amadé Zongo, a specialist in water management, who explained that this natural technique using plants is effective against river siltation. Thank you for listening and until next time.